Drawing-instrument



(No Model.)

L. F. RONDINBLLA. DRAWING INSTRUMENT.

No. 411.617. Patented Sept. 24, 1889'.

WITNESSES INVE A! T 0/? ll. PETERS, Phu'b-Utbognphun Washington. D. C.

UNITED STATES PATENT OFFICE.

1 LINO F. RONDINELLA, OF PHILADELPHIA, PENNSYLVANIA.

DRAWING-INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 411,617, dated September 24, 1889. Application filed April 16, 1889. Serial No, 307,492- (No model.)

To all whom it may concern:

Be it known that I, L1N0 F. RONDINELLA, a citizen of the United States, and a resident of the city and county of Philadelphia, State of Pennsylvania, have invented a new and useful Improvement in Drawing-Instruments, of which the following is a true and exact description, due reference being had to the accompanying drawings, which form a part of this application, and in which similar letters denote similar parts.

My invention relates to that class of drawing-instruments which are used in connection with the T-square or straight-edge in mechanical drawing for the purpose of plotting and measuring angles.

My invention has for its object the production of a single instrument which, used in connection with the ordinary T-square or straight-edge, will enable a draftsman to plot and measure any or all angles that are multiples of an angle of fifteen degrees. In the instruments for the purpose of plotting angles which are now used it is necessary in order to obtain all the angles which are multiples of fifteen degrees that two or more of these instruments shall be used, which is a source of annoyance and trouble.

My invention consists of a plane quadrilateral piece of wood or other suitable material, the sides of which are atsuch angles with each other that when used with the T- square or straight-edge the draftsman can readily lay out or measure any angle which is a multiple of fifteen degrees.

In the drawings, Figure 1 represents my improved drawing-instrument. Fig. 2 represents my improved drawing-instrument used in connection with the straight-edge. Fig. 3 represents my improved drawing-instrument used in connection with the straight-edge, the position of the instrument being varied in Figs. 2 and 3 one from the other.

A B, B O, O D, and A D represent the four sides of my improved drawing-instrument, the sides B A andA B forming a right angle, or an angle of ninety degrees, the side A B and the side B Gforming anangle of seventyfive degrees, the side B O and the side 0 D forming an angle of one hundred and thirtyfive degrees, and the side A D andthe side C D forming an angle of sixty degrees.

G represents a portion of an ordinary straight-edge or T-square. As shown in Figs. 2 and 3, and as is self-evident, the line D C, Fig. 2, and the line C B, Fig. 3, are common to both the drawing-instrument and the straight-edge. As may be readily seen, by varying the position of the various sides in reference to the straightedge any angle which is a multiple of fifeeen degrees can be readily drawn upon the paper or if drawn upon the paper can readily be measured.

Having now fully described my invention, what I claim, and desire to protect by Letters Patent, is

An improved drawing-instrument for plotting and measuring angles, which consists of a plane quadrilateral piece of wood or other suitable material, the sides of which form the angles of seventy-five degrees, ninety degrees, sixty degrees, and one hundred and thirtyfive degrees, respectively, the angles of seventy-five degrees and sixty degrees being adjacent to the right angle, while the angle of one hundred and thirty-five degrees is opposite to the right angle.

In testimony of which invention I have hereunto set my hand, at Philadelphia, Pennsylvania, this 13th day of April, 1889. 

